[ColinkaMir]

Closes #128

What was wrong

config.mjs compared WDK_GAS_MODE only against dry-run and native. With PIMLICO_API_KEY set, any other non-empty value became sponsored, which broadcasts. dryrun, dry_run, simulate and "dry-run " (trailing space) all turned broadcasting on while the operator was asking for a simulation.

The change

• src/config.mjs. The value is trimmed and lower-cased and must be one of the three documented in .env.example. Anything else sets config.gasModeError, naming the value and the accepted ones. A refused value also resolves to dry-run, so an entry point that never reads gasModeError still cannot broadcast on it.
• src/cli.mjs. On gasModeError the CLI prints gas mode: … and exits 1 before the banner, the wallet or the model, the way a missing NAD_POLICY file stops it (Fail startup when an explicit NAD_POLICY path is missing #108).
• Why a flag rather than a throw. My claim said config.mjs would throw. Six modules import it at load time, so a throw there ends the process with an uncaught stack trace instead of the one-line message Fail startup when an explicit NAD_POLICY path is missing #108 gives, and the CLI cannot catch it. The flag lets main() report it cleanly, and the dry-run fallback keeps the refusal safe in any path that does not check it.
• .env.example. One line saying any other value stops startup.
• Unchanged. An empty value keeps the auto-detection, no key still means dry-run, upper case is still accepted, and the confirmation lines and the mainnet acknowledgement are untouched.

Verified

test/gas-mode.test.mjs: config loaded in a child process, as reservoir-network.test.mjs does, and the built CLI run with the @qvac/sdk shim, as nfts-command.test.mjs does.

Test	What it checks	On main
a typo of a gas mode is refused, never read as sponsored	dryrun, dry_run, simulate, dry run, gasless with a key: refused with the value named, and gasMode is dry-run	fails
a refused value is refused without a key too	the same refusal without a key	fails
the documented values resolve as documented	dry-run, native, sponsored in any case, with padding	fails (padding)
the CLI stops before the banner or the wallet on every refused gas mode	dryrun, dry_run, simulate through the built CLI: exit 1, the message, no wallet initialisation, no gasless claim, no model call	fails
an empty value keeps the auto-detection	with and without a key; sponsored without a key still simulates	passes (control)

• Mutations. Dropping gasModeError from the dry-run fallback fails the first test; skipping the check in cli.mjs fails the CLI test.
• Full suite. npm run build && npm test: 634/634 on Node 22 (CI's major version) and on Node 20. The new file was rerun twice more with no flakes.